In:
Molecular Microbiology, Wiley, Vol. 98, No. 5 ( 2015-12), p. 946-962
Abstract:
The sugar nucleotide d TDP ‐ L ‐rhamnose is critical for the biosynthesis of the G roup A Carbohydrate, the molecular signature and virulence determinant of the human pathogen G roup A S treptococcus ( GAS ). The final step of the four‐step d TDP ‐ L ‐rhamnose biosynthesis pathway is catalyzed by d TDP ‐4‐dehydrorhamnose reductases ( RmlD ). RmlD from the G ram‐negative bacterium S almonella is the only structurally characterized family member and requires metal‐dependent homo‐dimerization for enzymatic activity. Using a biochemical and structural biology approach, we demonstrate that the only RmlD homologue from GAS , previously renamed GacA , functions in a novel monomeric manner. Sequence analysis of 213 G ram‐negative and G ram‐positive RmlD homologues predicts that enzymes from all G ram‐positive species lack a dimerization motif and function as monomers. The enzymatic function of GacA was confirmed through heterologous expression of gac A in a S . mutans rml D knockout, which restored attenuated growth and aberrant cell division. Finally, analysis of a saturated mutant GAS library using Tn‐sequencing and generation of a conditional‐expression mutant identified gac A as an essential gene for GAS . In conclusion, GacA is an essential monomeric enzyme in GAS and representative of monomeric RmlD enzymes in G ram‐positive bacteria and a subset of G ram‐negative bacteria. These results will help future screens for novel inhibitors of d TDP ‐ L ‐rhamnose biosynthesis.
Type of Medium:
Online Resource
ISSN:
0950-382X
,
1365-2958
DOI:
10.1111/mmi.2015.98.issue-5
Language:
English
Publisher:
Wiley
Publication Date:
2015
detail.hit.zdb_id:
1501537-3
Permalink